First
put in your microphone into the right place of your Soundcard (plug and card location
should have the same color). Now go to-> Start -> Programs -> Accessories
-> Entertainment -> Volume Controll

To
get to the microphone controls, pull down the Options menu and select Properties.

Select
the Recording Option and click OK.

Now
the Volume Control should have the Line In and Mic controls. Put the volume at
the max (the top) on both of these controls.